8,282 results match your criteria polymers undergo

Core-shell droplets and microcapsules formed through liquid-liquid phase separation of a colloid-polymer mixture.

Soft Matter 2021 Sep 22;17(36):8300-8307. Epub 2021 Sep 22.

Department of Physics and Biophysics, University of San Diego, San Diego, CA, 92110, USA.

Microcapsules allow for the controlled containment, transport, and release of cargoes ranging from pharmaceuticals to fragrances. Given the interest from a variety of industries in microcapsules and other core-shell structures, a multitude of fabrication strategies exist. Here, we report on a method relying on a mixture of temperature-responsive microgel particles, poly(-isopropylacrylamide) (pNIPAM), and a polymer which undergo fluid-fluid phase separation. Read More

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September 2021

Electrochemistry of Thin Films with In Situ/Operando Grazing Incidence X-Ray Scattering: Bypassing Electrolyte Scattering for High Fidelity Time Resolved Studies.

Small 2021 Sep 21:e2103213. Epub 2021 Sep 21.

Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.

Electroactive polymer thin films undergo repeated reversible structural change during operation in electrochemical applications. While synchrotron X-ray scattering is powerful for the characterization of stand-alone and ex situ organic thin films, in situ/operando structural characterization has been underutilized-in large part due to complications arising from supporting electrolyte scattering. This has greatly hampered the development of application relevant structure property relationships. Read More

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September 2021

Thin Thermoresponsive Polymer Films for Cell Culture: Elucidating an Unexpected Thermal Phase Behavior by Atomic Force Microscopy.

Langmuir 2021 Sep 17. Epub 2021 Sep 17.

Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), 8-2 Trubetskaya Street, Moscow 119991, Russia.

Application of poly--isopropylacrylamide (PNIPAM) and its more hydrophobic copolymers with --butylacrylamide (NtBA) as supports for cell sheets has been validated in numerous studies. The binary systems of these polymers with water are characterized by a lower critical solution temperature (LCST) in a physiologically favorable region. Upon lowering the temperature below the LCST, PNIPAM chains undergo a globule-to-coil transition, causing the film dissolution and cell sheet detachment. Read More

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September 2021

Stimuli-responsive supramolecular polymers from amphiphilic phosphodiester-linked azobenzene trimers.

Angew Chem Int Ed Engl 2021 Sep 16. Epub 2021 Sep 16.

University of Bern: Universitat Bern, Department of Chemistry and Biochemistry, SWITZERLAND.

An amphiphilic phosphodiester-linked azobenzene trimer has been exploited in the development of stimuli-responsive water-soluble supramolecular polymers. It can reversibly undergo thermal and photoisomerization between Z and E isomers in EtOH solution. Its self-assembly properties in aqueous medium have been investigated by spectroscopic and microscopic techniques, demonstrating that E - and Z -azobenzene trimers form supramolecular nanosheets and toroidal nanostructures, respectively. Read More

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September 2021

Design of Persistent and Stable Porous Radical Polymers by Electronical Isolation Strategy.

Angew Chem Int Ed Engl 2021 Sep 15. Epub 2021 Sep 15.

State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Institute of Polymer Optoelectronic Materials and Devices, No. 381 Wushan, Tianhe District, 510640, Guangzhou, CHINA.

Conjugated organic radical polymers with stable radical features are difficult to design because the π conjugation in the polymer backbones makes the radicals readily delocalize and tend to undergo covalent bonding processes. In this work, we report an electronical isolation strategy to design stable porous radical polymers by homocoupling reaction from a meta-position active monomer. The meta linkage ensures less conjugation in the polymer skeletons, localizes the resonant radicals, and prevent them from recombination. Read More

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September 2021

Comparison of biodegradable polyesters degradation behavior in sand.

J Hazard Mater 2021 08 25;416:126231. Epub 2021 May 25.

Institute for Polymers, Composites and Biomaterials - National Research Council of Italy, Via Campi Flegrei, 34, 80078 Pozzuoli (NA), Italy.

Sandy beaches represent environmental compartments particularly vulnerable to litter pollution, and they reflect the magnitude of pollution of adjacent compartments: water and coastal areas. The substitution of conventional polymers by biodegradable materials is generally considered as an alternative for reducing environmental accumulation of plastic debris. The present study is aimed to investigate the degradation of poly(lactic acid), poly(ε-caprolactone), poly(butylenesuccinate adipate) and poly(3-hydroxybutyrate) buried in sand for 267 days, simulating them as beach litter. Read More

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Light-modulated cationic and anionic transport across protein biopolymers.

Angew Chem Int Ed Engl 2021 Sep 7. Epub 2021 Sep 7.

Technion Israel Institute of Technology, Technion, Haifa, ISRAEL.

Light is a convenient source of energy and the heart of light-harvesting natural systems and devices. Here, we show light-modulation of both the chemical nature and ionic charge carrier concentration within a protein-based biopolymer that was covalently functionalized with photoacids or photobases. We explore the capability of the biopolymer-tethered photoacids and photobases to undergo excited-state proton transfer and capture, respectively. Read More

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September 2021

Weathering pathways and protocols for environmentally relevant microplastics and nanoplastics: What are we missing?

J Hazard Mater 2021 Aug 19;423(Pt A):126955. Epub 2021 Aug 19.

Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 0C5, Canada. Electronic address:

To date, most studies of microplastics have been carried out with pristine particles. However, most plastics in the environment will be aged to some extent; hence, understanding the effects of weathering and accurately mimicking weathering processes are crucial. By using microplastics that lack environmental relevance, we are unable to fully assess the risks associated with microplastic pollution in the environment. Read More

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Structure impact on photodynamic therapy and cellular contrasting functions of colloids constructed from dimeric Au(I) complex and hexamolybdenum clusters.

Mater Sci Eng C Mater Biol Appl 2021 Sep 31;128:112355. Epub 2021 Jul 31.

Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, 8 Arbuzov str., 420088 Kazan, Russian Federation.

Electrostatically driven self-assembly of [AuL] (L is cyclic PNNP ligand) with [{MoI}(L')] (L' = I, CHCOO) in aqueous solutions is introduced as facile route for combination of therapeutic and cellular contrasting functions within heterometallic colloids (Mo-Au). The nature of L' affects the size and aggregation behavior of crystalline Mo-Au aggregates, which in turn affect the luminescence of the cluster units incorporated into Mo-Au colloids. The spin trap facilitated electron spin resonance spectroscopy technique indicates that the level of ROS generated by Mo-Au colloids is also affected by their size. Read More

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September 2021

Structured Liquid Droplets as Chemical Sensors that Function Inside Living Cells.

ACS Appl Mater Interfaces 2021 Sep 1;13(36):42502-42512. Epub 2021 Sep 1.

Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Dr., Madison, Wisconsin 53706, United States.

We report that micrometer-scale droplets of thermotropic liquid crystals (LCs) can be positioned inside living mammalian cells and deployed as chemical sensors to report the presence of toxins in extracellular environments. Our approach exploits droplets of LC enclosed in semi-permeable polymer capsules that enable internalization by cells. The LC droplets are stable in intracellular environments, but undergo optical changes upon exposure of cells to low, sub-lethal concentrations of toxic amphiphiles. Read More

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September 2021

Catalyst-Free Spontaneous Polymerization with 100% Atom Economy: Facile Synthesis of Photoresponsive Polysulfonates with Multifunctionalities.

JACS Au 2021 Mar 19;1(3):344-353. Epub 2021 Feb 19.

Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, and Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.

Photoresponsive polymers have attracted extensive attention due to their tunable functionalities and advanced applications; thus, it is significant to develop facile synthesis strategies, extend polymers family, and establish various applications for photoresponsive polymers. Herein, we develop a catalyst-free spontaneous polymerization of dihaloalkynes and disulfonic acids without photosensitive monomers for the synthesis of photoresponsive polysulfonates at room temperature in air with 100% atom economy in high yields. The resulting polysulfonates could undergo visible photodegradation with strong photoacid generation, leading to various applications including dual-emissive or 3D photopatterning, and practical broad-spectrum antibacterial activity. Read More

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Metathesis Cascade-Triggered Depolymerization of Enyne Self-Immolative Polymers.

Angew Chem Int Ed Engl 2021 Aug 27. Epub 2021 Aug 27.

Boston College, Department of Chemistry, 2609 Beacon St., Merkert Chemistry Center 214B, 02467, Chestnut Hill, UNITED STATES.

A novel class of enyne self-immolative polymers (SIPs) capable of metathesis cascade-triggered depolymerization is reported. Studies on model compounds established 1,6-enyne structures for efficient metathesis cascade reactions. SIPs incorporating the optimized 1,6-enyne motif were prepared via both polycondensation and iterative exponential growth approaches. Read More

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Exohedral Functionalization of Fullerene by Substituents Controlling of Molecular Organization for Spontaneous C Dimerization in Liquid Crystal Solutions and in a Bulk Controlled by a Potential.

Polymers (Basel) 2021 Aug 22;13(16). Epub 2021 Aug 22.

Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.

A study was carried out on the possibility of orderly and spontaneous dimerization at room temperature of C cages in fullerene liquid crystal fullerene dyads (R-C). For this purpose, dyads with a structural elements feature supporting π-stacking and Van der Waals interactions were tested, due to the presence of terthiophene donors linked through an α-position or dodecyloxy chains. In addition, this possibility was also tested and compared to dyads with shorter substituents and the pristine C. Read More

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SEM/EDS Evaluation of the Mineral Deposition on a Polymeric Composite Resin of a Toothpaste Containing Biomimetic Zn-Carbonate Hydroxyapatite (microRepair) in Oral Environment: A Randomized Clinical Trial.

Polymers (Basel) 2021 Aug 16;13(16). Epub 2021 Aug 16.

Unit of Orthodontics and Pediatric Dentistry, Section of Dentistry, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy.

Toothpastes containing biomimetic hydroxyapatite have been investigated in recent years; the behavior of this material in the oral environment has been evaluated directly on dental enamel showing a marked remineralizing activity. To propose microRepair-based toothpastes (Zn-carbonate hydroxyapatite) for the domiciliary oral hygiene in patients with dental composite restorations, the aim of this study was to evaluate the deposition of Zn-carbonate hydroxyapatite on a polymeric composite resin with Scanning Electron Microscopy/Energy-Dispersive X-ray Spectrometry (SEM/EDS) analysis. Twenty healthy volunteers underwent the bonding of 3 orthodontic buttons on the vestibular surfaces of upper right premolars and first molar. Read More

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Preparation and Characterization of Salt-Mediated Injectable Thermosensitive Chitosan/Pectin Hydrogels for Cell Embedding and Culturing.

Polymers (Basel) 2021 Aug 10;13(16). Epub 2021 Aug 10.

CNR NANOTEC-Institute of Nanotechnology c/o Campus Ecotekne, via Monteroni, 73100 Lecce, Italy.

In recent years, growing attention has been directed to the development of 3D in vitro tissue models for the study of the physiopathological mechanisms behind organ functioning and diseases. Hydrogels, acting as 3D supporting architectures, allow cells to organize spatially more closely to what they physiologically experience in vivo. In this scenario, natural polymer hybrid hydrogels display marked biocompatibility and versatility, representing valid biomaterials for 3D in vitro studies. Read More

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Investigating Nanoparticle Organization in Polymer Matrices during Reaction-Induced Phase Transitions and Material Processing.

ACS Appl Mater Interfaces 2021 Sep 25;13(35):42104-42113. Epub 2021 Aug 25.

Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.

Controlling nanoparticle organization in polymer matrices has been and is still a long-standing issue and directly impacts the performance of the materials. In the majority of instances, simply mixing nanoparticles and polymers leads to macroscale aggregation, resulting in deleterious effects. An alternative method to physically blending independent components such as nanoparticle and polymers is to conduct polymerizations in one-phase monomer/nanoparticle mixtures. Read More

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September 2021

Characterization of commercial PLGAs by NMR spectroscopy.

Drug Deliv Transl Res 2021 Aug 20. Epub 2021 Aug 20.

Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI, 48109, USA.

Poly(lactic-co-glycolic acid) (PLGA) is among the most common of biodegradable polymers studied in various biomedical applications such as drug delivery and tissue engineering. To facilitate the understanding of the often overlooked impact of PLGA microstructure on important factors affecting PLGA performance, we measured four key parameters of 17 commonly used commercial PLGA polymers (Expansorb®, Resomer®, Purasorb®, Lactel®, and Wako®) by NMR spectroscopy. HNMR and CNMR spectra were used to determine lactic to glycolic ratio (L/G ratio), polymer end-capping, glycolic blockiness (Rc), and average glycolic and lactic block lengths (L and L). Read More

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En route to dynamic life processes by SNARE-mediated fusion of polymer and hybrid membranes.

Nat Commun 2021 08 17;12(1):4972. Epub 2021 Aug 17.

Electrochemical Energy Conversion, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany.

A variety of artificial cells springs from the functionalization of liposomes with proteins. However, these models suffer from low durability without repair and replenishment mechanisms, which can be partly addressed by replacing the lipids with polymers. Yet natural membranes are also dynamically remodeled in multiple cellular processes. Read More

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SuFExable polymers with helical structures derived from thionyl tetrafluoride.

Nat Chem 2021 09 16;13(9):858-867. Epub 2021 Aug 16.

Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, USA.

Sulfur(VI) fluoride exchange (SuFEx) is a category of click chemistry that enables covalent linking of modular units through sulfur(VI) connective hubs. The efficiency of SuFEx and the stability of the resulting bonds have led to polymer chemistry applications. Now, we report the SuFEx click chemistry synthesis of several structurally diverse SOF-derived copolymers based on the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers). Read More

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September 2021

Repurposing of nifedipine loaded in situ ophthalmic gel as a novel approach for glaucoma treatment.

Biomed Pharmacother 2021 Oct 9;142:112008. Epub 2021 Aug 9.

Department of Pharmaceutics, Faculty of Pharmacy, Modern University for Technology and Information (MTI), Cairo, Egypt. Electronic address:

Glaucoma is a chronic eye disease characterized by elevated intraocular pressure (IOP) which causes severe complications to the eyes and may lead to vision loss. The effective treatment of such diseases motivated the search for novel and unique drugs and delivery systems. It has been reported that, nifedipine (NF) is effective in reducing the elevated IOP due to vasodilatation of eye vascular smooth muscles. Read More

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October 2021

Induction and expansion of human PRRX1 limb-bud-like mesenchymal cells from pluripotent stem cells.

Nat Biomed Eng 2021 08 9;5(8):926-940. Epub 2021 Aug 9.

Department of Regenerative Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.

Current protocols for the differentiation of human pluripotent stem cells (hPSCs) into chondrocytes do not allow for the expansion of intermediate progenitors so as to prospectively assess their chondrogenic potential. Here we report a protocol that leverages PRRX1-tdTomato reporter hPSCs for the selective induction of expandable and ontogenetically defined PRRX1 limb-bud-like mesenchymal cells under defined xeno-free conditions, and the prospective assessment of the cells' chondrogenic potential via the cell-surface markers CD90, CD140B and CD82. The cells, which proliferated stably and exhibited the potential to undergo chondrogenic differentiation, formed hyaline cartilaginous-like tissue commensurate to their PRRX1-expression levels. Read More

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Enzymatic Synthesis of Muconic Acid-Based Polymers: Trans, Trans-Dimethyl Muconate and Trans, β-Dimethyl Hydromuconate.

Polymers (Basel) 2021 Jul 29;13(15). Epub 2021 Jul 29.

Macromolecular Chemistry and New Polymeric Materials, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.

The vast majority of commodity polymers are acquired from petrochemical feedstock, and these resources will plausibly be depleted within the next 100 years. Therefore, the utilization of carbon-neutral renewable resources for the production of polymers is crucial in modern green chemistry. Herein, we report an eco-friendly strategy that uses enzyme catalysis to design biobased unsaturated (co)polyesters from muconic acid derivatives. Read More

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New Insights on Expandability of Pre-Cured Epoxy Using a Solid-State CO-Foaming Technique.

Polymers (Basel) 2021 Jul 24;13(15). Epub 2021 Jul 24.

Department of Polymer Engineering, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany.

Foaming an epoxy is challenging because the process involves the curing reaction of epoxy and hardener (from monomer to oligomer, to a gel and a final three-dimensional crosslinked network) and the loading of gas phase into the epoxy phase to develop the cellular structure. The latter process needs to be carried out at the optimum curing stage of epoxy to avoid cell coalescence and to allow expansion. The environmental concern regarding the usage of chemical blowing agent also limits the development of epoxy foams. Read More

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Recent developments in selenium-containing polymeric micelles: prospective stimuli, drug-release behaviors, and intrinsic anticancer activity.

J Mater Chem B 2021 Sep 5;9(34):6770-6801. Epub 2021 Aug 5.

Department of Chemistry, College of Natural and Computational Sciences, Debre Markos University, P.O. Box 269, Debre Markos, Ethiopia.

Selenium is capable of forming a dynamic covalent bond with itself and other elements and can undergo metathesis and regeneration reactions under optimum conditions. Its dynamic nature endows selenium-containing polymers with striking sensitivity towards some environmental alterations. In the past decade, several selenium-containing polymers were synthesized and used for the preparation of oxidation-, reduction-, and radiation-responsive nanocarriers. Read More

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September 2021

Structural insights into how Prp5 proofreads the pre-mRNA branch site.

Nature 2021 08 4;596(7871):296-300. Epub 2021 Aug 4.

Cellular Biochemistry, MPI for Biophysical Chemistry, Göttingen, Germany.

During the splicing of introns from precursor messenger RNAs (pre-mRNAs), the U2 small nuclear ribonucleoprotein (snRNP) must undergo stable integration into the spliceosomal A complex-a poorly understood, multistep process that is facilitated by the DEAD-box helicase Prp5 (refs. ). During this process, the U2 small nuclear RNA (snRNA) forms an RNA duplex with the pre-mRNA branch site (the U2-BS helix), which is proofread by Prp5 at this stage through an unclear mechanism. Read More

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Stimuli-Responsive Block Copolymer Micelles Based on Mussel-Inspired Metal-Coordinated Supramolecular Networks.

Macromol Rapid Commun 2021 Sep 6;42(17):e2100312. Epub 2021 Aug 6.

Rubber Technology Centre, Indian Institute of Technology Kharagpur, 721302, India.

Amphiphilic diblock copolymers containing dopamine and zwitterions are synthesized via the RAFT polymerization method, which undergo temperature-mediated micellization in aqueous media. The presence of catechol moiety in dopamine is exploited to form pH-responsive cross-links with ferric ions (Fe ) at different pH value. Herein, a comprehensive study of the effect of pH as well as temperature on the size and solution behavior of these cross-linked micelles is presented. Read More

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September 2021

Study of non-uniform axial magnetic field induced deformation of a soft cylindrical magneto-active actuator.

Soft Matter 2021 Aug 2;17(32):7498-7505. Epub 2021 Aug 2.

State Key Laboratory of Fluid Power & Mechatronic System, Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Center for X-Mechanics, Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China.

Magneto-active polymers (MAPs) can undergo rapid and noticeable deformation through external wireless magnetic stimulation, offering a possibility to develop potential applications such as in actuators, flexible micro-grippers, soft robots, etc. In this paper, a theoretical model is presented to depict the relationship between nonlinear deformation and the external mechanical load applied on cylindrical samples in the presence of magnetic fields generated by an electromagnet. The geometrical and electromagnetic properties of the electromagnet are explicitly modeled in COMSOL Multiphysics based on the measured data. Read More

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Microplastic degradation as a sustainable concurrent approach for producing biofuel and obliterating hazardous environmental effects: A state-of-the-art review.

J Hazard Mater 2021 09 11;418:126381. Epub 2021 Jun 11.

Mechanical Engineering Department, De La Salle University, 2401 Taft Avenue, 0922 Manila, Philippines.

As plastics have been omnipresent in society ever since their introduction in 1907, global plastic production has ballooned in the 20th century or the Plasticene Era (Plastic Age). After their useful life span, they deliberately or accidentally, are disposed of in the environment. Influenced by different factors, plastics undergo fragmentation into microplastics (MPs) and present hazardous risks in all life forms including humans. Read More

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September 2021

Effect of Protonation on Optical and Electrochemical Properties of Thiophene-Phenylene-Based Schiff Bases with Alkoxy Side Groups.

J Phys Chem B 2021 08 27;125(30):8588-8600. Epub 2021 Jul 27.

Electroactive Polymers and Plasmochemistry Laboratory, "Petru Poni" Institute of Macromolecular Chemistry, Aleea Grigore Ghica Vodă nr. 41A, Iaşi 700487, Romania.

Three polyazomethines and their corresponding model compounds were protonated with trifluoroacetic acid, and its effect on their optical (UV-vis absorption and photoluminescence) properties and electrochemical behavior has been studied, in the context of the presence and elongation of alkoxy side groups. Moreover, the effect of environment dielectric constants (i.e. Read More

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Vitrification of octonary perylene mixtures with ultralow fragility.

Sci Adv 2021 Jul 16;7(29). Epub 2021 Jul 16.

Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.

Strong glass formers with a low fragility are highly sought-after because of the technological importance of vitrification. In the case of organic molecules and polymers, the lowest fragility values have been reported for single-component materials. Here, we establish that mixing of organic molecules can result in a marked reduction in fragility. Read More

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